In medium bowl, combine flour, baking powder, and salt. Mix well. Add shortening and cut in until mixture is crumbly. Stir in hot water in two parts, mixing well after each. Lightly knead on floured surface, 20-30 times. Cover and let rest for 20 minutes.
Divide dough into 12 pieces, forming each into a ball. Allow to rest for 10 minutes. On floured surface, roll out balls of dough very thin to form a 9" circle.
Heat a cast iron griddle to medium-high heat. (Test temperature by sprinkling water on griddle. If it sizzles, it's ready.) Cook tortillas on each side for 30 seconds, tamping down air bubbles as needed. Remove from griddle when brown spots appear and cover with a towel to keep warm or place in a terracotta tortilla warmer. Serve immediately in your favorite Mexican recipe. Store extras in seal-tight container. Makes 12 tortillas.